正则表达式匹配精确的字符数？

我需要一个正则表达式，将匹配任何三个大写字母，所以 AAA 或 ABC 或 DKE。但它不能匹配四个或更多，像 AAAA 或 ABCDEF 或 abbB。

我的解决方案: ^([A-Z][A-Z][A-Z])$

问题 :

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最佳答案

What you have is correct, but this is more consice:

^[A-Z]{3}$

小开

Your solution is correct, but there is some redundancy in your regex.
The similar result can also be obtained from the following regex:

^([A-Z]{3})$

The {3} indicates that the [A-Z] must appear exactly 3 times.